Pitman



(No Model.)

G. B. PORTER. PITMAN.

No. 497,815. Patented May 23, 1893.

Greer UNITED STATES PATENT OFFICE.

GEORGE B. PORTER, OF COVENTRY, ASSIGNOR OF ONE-HALF TO J. IRVING BARR AND FRED BARR,

PITMAN.

SPECIFICATION forming part of Letters Patent No. 497,815, dated May 23, 1893.

Application filed May 20, 1891.

To all whom it may concern:

Be it known that I, GEORGE E. PORTER, a citizen of the United States, residing at V- entry, county of Ohenango, and State of New York, have invented a new and useful Improvement in Pitmen', of which the following is a specification.

This invention relates to pitmen or connecting-rods, such as are used for example in I0 sewing-machines, and is designed to overcome the dead center so that the machine will run more easily and start more readily than with the pitmen in ordinary use.

The invention is illustrated in the accompanying drawings, wherein Figure 1,is a side view of the improved pitman, and Fig. 2, is a central longitudinal section of the same.

The pitman is composed of a main stem A A, and a pivoted member B at the working end of the pitman. The main stem of the pitnian is preferably formed in two sections A, A, slidable one upon the other so as to make the length of the pitman adj nstable, the adjustment being controlled by a set-screw 00.

2 5 At its upper or forward end the main stem of the pitman, that is, the section A thereof, is formed with two forking branches at a. Across both branches at a, near their point of origin and on opposite sides thereof, are se- 3 cured plates 0 cforming journal bearings for the pivot b of the pivoted member B of the pitman. The inner end of the pivoted member B rests in the crotch of the fork a a, and the pivoted member B is capable of a lateral vibration or oscillation between the two branches of the fork, the ends of the branches to a serving as stops to limit the extent of the vibratory or oscillatory movement of the pivoted member. Plates d (1 may be secured across the outer ends of the branches to a to prevent any possible edgewise displacement of the pivoted member. The ends of the branches a a are beveled on the inside, and the adjacent portions of the pivoted member B are shaped correspondingly with the said beveled ends, so that the sides of the pivoted member will seat smoothly against the ends of thebranches, thus diminishing friction and wear at the points of contact.

The pivoted member B is normally held in Serial No. 39 3,494- (No model.)

a medial position between thetwo branches at a and in line with the main stem of the pitman, by means of a spring or springs, the springs O D being shown in the drawings for this purpose. The spring 0 is shown as formed from the same piece of metal as one of the journal plates 0, from whence it extends upward or forward and enters an eye or slotted projection atthe end of the pivoted member B. The tendency of the spring 0 is to restore the pivoted member to its central position when it is pressed to either side.

The spring D is placed within the branches a a of the pitman stem, passing between the inner end of the pivoted member B and the crotch of the fork and extending up on each side of the pivoted member, as shown, the two ends of the spring D pressing against opposite sides of the pivoted member, and so having the same effect as the spring 0, namely, to maintain the pivoted member B in its central or intermediate position.

The particular forms of spring shown are not essential to the invention, since any arrangement of springs may be adopted which will conveniently accomplish the desired result.

While the springs acting upon the pivoted member B give the two portions of the pitman sufficient relative firmness to insure the So proper working of the pitman, they at the same time provide a flexible joint which has the effect of greatly facilitating the operation. During the working of the pitman, the pivoted member B vibrates or oscillates between the branches a a of the fork, as indicated by the dotted lines in Fig. 1 of the drawings. If, for example, the pitman is arranged horizontally on the machine, the pivoted member B is pressed toward the branch a above 0 it at each forward stroke of the pitman, and then toward the branch at below it on the return or backward stroke; and at the turning point between the two strokes, that is at the instant when the dead center is supposed 9 5 to occur, the springs O D act to carry the parts past the dead center, thus insuring the easy running of the machine. The outer end 0' of the section A of the pitman stem is adapted to connect with the source of power,

and the outer end 0 of the pivoted member B is adapted to connect with the crank to which power is to be applied.

When the length of the pitman stem has been properly adjusted, and the two sections A A secured together by the set-screw 00 or its equivalent, the two sections practically constitute a simple integral stem.

The adjustability of the pitman constitutes no part of the present invention, and generally speaking the pitman may be said to consist of two parts or members, namely, the entire pitman stem (designated A in the claims) and the pivoted member B.

It will of course be understood that the vibration of the pivoted member Bis in the plane of movement of the pitman, and that the eifect of the flexible joint between the two members of the pitman is aconstant one while the machine is in operation, the effect of the joint being analogous to that of the wrist-joint between the hand and arm of a person manually rotating a crank, the forearm being considered the equivalent of the pitman-stem, and the hand the equivalent of the pivoted member.

I claim as my invention- A pitman comprising two membersA B, adapted to connect respectively with a source of power and a crank to be driven, and pivoted together to permit fiexure in the plane of movement of the pitman, and restoring means, as a spring or springs, tending to counteract such fiexure, substantially as set forth.

2. A pitman having a pivoted member 15 constituting one of the ends thereof and adapted to connect with a crank to which power is to be applied, said pivoted member being capable of a vibratory movement in the plane of movement of the pitman, in combination with stops for limiting the extent of Vibration of said pivoted member,and aspring or springs acting upon said pivoted member, substantially as set. forth.

3. The pitman stem A adapted at one end to connect with a source of power and having the other end forked, a pivoted member B pivoted between thebranchesa a of the forked end of the stem and capable of vibration between the said branches at a, and a spring or springs which normally hold said pivoted member in a central position between said branches at a, said pivoted member B being adapted to connect with the wrist of a crank, substantially as set forth.

4. The pitman stem A adapted at one end to connect with a source of power and having the other end forked, platesc c secured across said forked end of the pitman stem on opposite sides thereof, and a pivoted member B journaled in and between said plates 0 c, the inner end of said pivoted member seating in the crotch of the fork and its outer end being adapted to connect with the wrist of a crank, substantially as set forth.

5. The pitman stem A forked at its forward end, the plates 0 c secured across and on 0pposite sides of said pitman stem, and the pivoted member B journaled in said plates 0 c, in combination with the spring 0 formed integral with one of said journal plates and acting upon the pivoted member B at its extremity, substantially as set forth.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence of two witnesses.

GEORGE E. PORTER.

Witnesses:

FRED E. BARR, IRVING BARR. 

